Tunisia's ruling Nidaa Tounes party said on Friday it had frozen the prime minister's membership in the latest escalation in a row between the premier and the president's son.

Prime Minister Youssef Chahed said in May that the son, Hafedh Caid Essebsi - who is the leader of Nidaa Tounes - had destroyed the party and that the internal crisis had affected state institutions.

"The party decided to freeze the membership of Chahed," Nidaa Tounes said in a statement.

Caid Essebsi had called for Chahed's dismissal because of what he said was his government's failure to revive the economy.

His call was supported by the powerful UGTT union, which rejected economic reforms proposed by the prime minister.

But coalition partners Ennahda rejected calls to dismiss Chahed and said the exit of the prime minister would hit stability at a time when the country needed economic reforms.

"Despite the lack of political support for the government, we will move ahead with economic reforms next year, including the reform of subsidies and social funds," Chahed said on Friday.

In July, President Beji Caid Essebsi called Chahed, who has been prime minister since 2016, to step down or seek a confidence vote if the country's political and economic crisis continues, withdrawing his support for the premier.

The North African country has been hailed as the Arab Spring's only democratic success because protests toppled longtime-leader Zine El Abidine Ben Ali in 2011 without triggering the kind of violent upheavals seen in Syria and Libya.

But since 2011, nine cabinets have failed to resolve Tunisia's economic problems, which include high inflation and unemployment, and impatience is rising among lenders such as the International Monetary Fund, which have helped keep the country afloat.